This 1972 Sinclair Executive calculator look like the iPhone 5

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Executive_medium

via www.nvg.ntnu.no

Sinclairexecutive_1a_medium

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Sinclairexecmemory_3_jpg_medium

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Sinclairexecmemory_2_jpg_medium

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The Sinclair Executive was the world's first pocket calculator,launched in August 1972 at a price of £79.95 + VAT. The advert described it as being "as thick as a cigarette packet", reflecting Clive Sinclair's stated belief that "One must always bear a packet of cigarettes in mind as the ideal size"; it was a running joke at Radionics that Sinclair, who smoked 40 cigarettes a day at the time, designed everything to be the size of a packet of 20.

Links:

http://en.wikipedia.org/wiki/Sinclair_Executive

http://www.nvg.ntnu.no/sinclair/calculators/executive.htm

http://www.vintagecalculators.com/html/sinclair___the_pocket_calculat.html